<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>背景</title>
		<style type="text/css">
			/*无宽高的div，设置背景色也无意义*/
			.box{
				width:100px;
				height:100px;
				/*不简写*/
				/* background-color: #008000; */
				/*简写*/
				/* background:#000; */
				background-color: rgb(7,196,95);
			}
			.xbox{
				width:100px;
				height:100px;
				background-color: rgba(7,196,95,.5);
			}
		</style>
	</head>
	<body>
		<div class="box"></div>
		<div class="xbox"></div>
	</body>
</html>
